MRI magnet with enhanced patient entry and positioning

ABSTRACT

A magnetic resonance imaging (MRI) magnet in combination with a mobile patient-positioning device, including a patient support and a method of using same for positioning patients for MRI scanning. The patient support is rotatable through a range of orientations. The patient disposed on the patient-positioning device in a predetermined orientation can then be moved horizontally into and out of a patient-receiving space in the MRI magnet at the predetermined angle or orientation. A preferred embodiment includes a plurality of patient-positioning devices in which a series of patients can be placed in a ready state while one patient is within the patient-receiving space. As an alternative embodiment, the patient may be moved vertically into position for MRI scanning by way of an elevator which is actuatable from the floor below the patient receiving space. This elevator also may be used in combination with the patient-positioning device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of a co-pending U.S.patent application Ser. No. 08/978,084, filed Nov. 25, 1997 (the '084application). The '084 application claims the benefit of U.S.Provisional Application Ser. Nos. 60/031,610, filed Nov. 27, 1996, and60/032,589, filed Nov. 29, 1996, the disclosures of which areincorporated by reference herein. The '084 application incorporates byreference U.S. patent application Ser. No. 08/975,913, filed Nov. 21,1997, the disclosure of which is incorporated by reference herein. The'084 application is a Continuation-in-Part of U.S. patent applicationSer. No. 07/993,072, filed Dec. 18, 1992, now U.S. Pat. No. 6,023,165 ofRaymond V. Damadian, Gordon T. Danby, John W. Jackson, Hank Hsieh, TerryMorrone, and Timothy Damadian and entitled Nuclear Magnetic ResonanceApparatus and Methods of Use and Facilities for Incorporating the Same.

BACKGROUND OF THE INVENTION

The present invention relates generally to magnetic resonance imaging or“MRI” and particularly to an apparatus and methods for entering andpositioning a patient into an MRI system.

The magnetic resonance or “MR” scanners commonly used today require apatient who is to be scanned to be oriented with the long axis of thebody in a horizontal position. This aspect of MR scanners or MRI is theresult, in part, of the magnet design, the patient-positioning systemused to position the patient within the magnet, and the methods designedto accommodate these features of the MRI device.

Thus, of necessity, MRI normally is restricted to the situation wheregravitational force is exerted on the human body when it is horizontallyoriented. However, a human body has other natural positions. These areupright or vertical positions, or sitting positions, where the forces onthe body are effectively rotated 90 degrees with respect to thehorizontal orientation. MR scanning of the body, oriented in a verticalor sitting position, is not presently achievable with commerciallyavailable systems.

Attempts have been made heretofore to provide MR scanning of a patientin a vertical position. For example, in U.S. Pat. No. 5,153,546, asuperconductive air-core MRI magnet is shown which can be rotated by anoperator so that a patient can walk into a patient receiving spacewithin the magnet and be imaged. However, when in the patient receivingspace of this reference, the patient does not have any support forsustaining and maintaining the patient's relative orientation andposition. Also, once the magnet has been rotated to accommodate apatient in a vertical orientation, there would be no room for aphysician or attending personnel to access the patient during a scan.Also, if it is desirable to have a second patient scanned in ahorizontal orientation, the MRI magnet would have to be rotated back tothe original position by the operator. This would cause a delay beforethe next patient can be scanned.

Thus, it is desirable to have an apparatus and methods which wouldpermit MR scanning to be performed with the human body oriented in avertical or near vertical position or in a sitting position where theMRI magnet does not necessarily have to change its orientation. It alsois desirable to have a patient support or rest to accommodate variousorientations of the patient. Further, it is desirable to have anapparatus and methods which provide for a series of patients to bescanned in a time saving manner.

SUMMARY OF THE INVENTION

The present invention addresses these needs. The preferred apparatus andmethods of this invention allow such vertical or near verticalorientation during scanning, and, most preferably, also allow otherorientations of the patient. The present invention also may provideenhanced efficiency and convenience in scanning multiple patients. Inaddition to providing a vertical or near vertical orientation duringscanning, a preferred embodiment allows a physician and associatedmedical personnel to have access to the patient during a scanningsession so as to, by way of example, perform MRI-assisted surgery.

One aspect of the present invention provides a method of magneticresonance imaging comprising the steps of: positioning a first patientto be scanned in a patient-receiving space of a magnetic resonanceimaging magnet and conducting a magnetic resonance scan of the firstpatient; during the magnetic resonance scan of the first patient,positioning a second patient in a desired orientation on a mobilepatient-positioning device disposed remote from the patient-receivingspace; moving the first patient out of the patient-receiving space andmoving the second patient into the patient-receiving space by moving themobile patient-positioning device while maintaining the second patientin the desired orientation; and conducting a magnetic resonance scan ofthe second patient while the second patient is disposed in thepatient-receiving space on the mobile patient-positioning device.

A further aspect of the present invention provides a method of magneticresonance imaging comprising the steps of: positioning a series ofpatients on a plurality of mobile patient-positioning devices so thateach patient is disposed on one associated mobile patient-positioningdevice which is brought to a desired orientation for that patient whilethe patient and the associated mobile patient-positioning device aredisposed remote from a patient-receiving space of a magnetic resonanceimaging magnet; moving the patients into and out of thepatient-receiving space in sequence by moving the mobilepatient-positioning devices so that each patient is moved into thepatient-receiving space while such patient is maintained in the desiredorientation; and conducting magnetic resonance scans of the patients,the aforesaid steps being coordinated so that at least some of thepatients are brought to the desired orientation while other patients aredisposed in the patient-receiving space.

Yet another aspect of the present invention provides a mobilepatient-positioning device comprising: a frame; a patient supportmounted to the frame for movement through a range of orientationsrelative to the frame; means for allowing movement of the frame relativeto a magnetic resonance imaging magnet so that a patient on the patientsupport can be positioned in a patient-receiving space of such magnetwith the support in any orientation. Preferably, the means for allowingmovement includes wheels supporting the frame. The foregoingarrangements facilitate rapid scanning of patients in sequence. The MRIsystem need not remain idle while a new patient is adjusted to theproper position.

Desirably, the mobile patient-positioning device further comprises meansfor lifting the patient support upwardly and downwardly relative to theframe.

Alternatively or additionally, an embodiment of the present inventionincludes a mobile patient-positioning device in combination with anelevator mounted in a fixed location relative to the magnet, theelevator being adapted to move the frame upwardly and downwardlyrelative to the magnet when the frame is disposed adjacent the magnet.The arrangements allow scanning of various parts of the patient's body.

A further aspect of the present invention provides a magnetic resonanceimaging magnet comprising: a magnet frame; a pair of pole faces spacedapart from one another along a horizontal pole axis and defining apatient-receiving space therebetween; supports holding the frame on orabove a floor of a structure so that a patient may enter thepatient-receiving space by moving across the floor of the structure; andmagnetic flux generating means for providing magnetic flux in thepatient-receiving space.

Preferably the magnet may further comprise an elevator for raising orlowering a patient relative to the frame. More preferably, the elevatorhas a platform and the elevator is arranged to move the platform into aboarding position wherein the platform is close to the floor so that apatient standing on the floor of the structure can step onto theplatform or can be wheeled onto the platform on a wheeled carriage.

In another preferred embodiment of the present invention, there isprovided an MRI magnet comprising a magnet frame; a pair of pole facesspaced apart from one another along a horizontal pole axis and defininga patient-receiving space therebetween; supports for holding the frameon or above the floor of a structure so that a patient may enter thepatient-receiving space by moving across the floor of the structure; andmagnetic flux generating means for providing magnetic flux in thepatient-receiving space; in combination with a mobilepatient-positioning device. The mobile patient-positioning deviceincludes a frame; a patient support mounted to the frame for movementthrough a range of orientations relative to the frame; and means forallowing movement of the frame relative to the magnet so that a patienton the patient support can be positioned in a patient-receiving space ofthe magnet with the patient support in any desired orientation.

Preferably, the frame is a ferromagnetic frame providing a flux returnpath between the poles. Desirably, the frame is generally C-shaped.

More preferably, the flux generating means is arranged to provide amagnetic field strength of at least about 3 kilogauss in thepatient-receiving space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a magnetic resonance imaging magnet for usewith the apparatus and methods in accordance with one embodiment of theinvention;

FIG. 2 is a front elevation view of the magnet of FIG. 1;

FIG. 3 is a side elevation view of the magnet and a patient-positioningdevice in accordance with the first embodiment of the invention;

FIG. 4 is a side elevation view of the system of FIG. 3 showing thepatient support of the patient-positioning device of FIG. 3 in avertical position;

FIG. 5 is a side elevation view of the patient-positioning device ofFIG. 3 showing the patient support of the patient-positioning device ina horizontal position;

FIG. 6 is a side elevation view of the patient-positioning device ofFIG. 3 showing the patient support of the patient-positioning device ata position between horizontal and vertical;

FIG. 7 is a top plan view of the patient-positioning device of FIG. 3;

FIG. 8A is a top plan view of the patient-positioning device of FIG. 3with the patient rest in the vertical position;

FIG. 8B is a side elevation view of the patient-positioning device ofFIG. 8A;

FIG. 9 is a front elevation view of the magnet of FIG. 1 and apatient-positioning device in accordance with a further embodiment ofthe invention;

FIG. 10 is a side elevation view of the magnet and patient-positioningdevice of FIG. 9;

FIG. 11 is a plan view of the magnet and patient-positioning device ofFIG. 9;

FIG. 12 is a front elevation view of the magnet of FIG. 1 in accordancewith a further embodiment of the invention where the flux return frameor yoke is below a false floor;

FIG. 13 is a top plan view of the magnet of FIG. 12; and

FIG. 14 is a side elevation view of the magnet of FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Apparatus in accordance with one embodiment of the present invention, asshown in FIGS. 1-8, includes a magnetic resonance imaging magnet 9 whichmay include a ferromagnetic flux return frame or yoke 10 defining a pairof opposed poles 12 projecting towards one another along ahorizontally-oriented pole axis 14 (FIG. 2) and defining a patientreceiving space 16. Flux generating means such as permanent magnetsassociated with frame 10, superconducting coils encircling portions ofthe flux return frame 10 or, most preferably, resistive electrical coils18 encircling portions of the frame 10 are provided. As illustrated, theresistive coils 18 encircle the frame 10 adjacent poles 12. Thestructure of the C-shaped magnet may be as illustrated and described inco-pending, commonly assigned U.S. patent application Ser. No.07/993,072 filed Dec. 18, 1992, the disclosure of which is herebyincorporated by reference herein. The magnet defines an open directionof patient entry as indicated by arrow 20 in FIG. 1, allowing movementof a patient into patient receiving space 16. The magnet is supported ona floor 22 of a building, vehicle or other structure by a set of columns24, so that the pole axis 14 and the patient-receiving space 16 aredisposed above the floor 22.

One or, more preferably, several mobile patient-positioning devices 30are provided. One such device is shown in FIGS. 3-8. Eachpatient-positioning device is movable relative to the magnet 9independently of the other patient-positioning devices. Thus, thepreferred patient-positioning device 30 illustrated includes a frame 32mounted on wheels 34 so that the device 30, with a patient thereon canbe moved into and out of the patient-receiving space 16 of the magnet 9by an operator manipulating the device 30 with a handle 36. The device30 further includes a patient support 38 movably mounted to frame 32 asby a swingable pivot and lock arrangement 40 and linear movement device42. Patient support 38 can be swung or adjusted between the horizontalposition depicted in FIG. 3 and a vertical position depicted in FIG. 4,and also can be moved to tilted positions (see FIG. 6) at which thepatient support 38 makes oblique angles with the horizontal. As anexample of such an oblique angle, a patient may be placed in aTrendelenburg position and or a counter-Trendelenburg position.Generally, a Trendelenburg position is one where the patient support 38is tilted from horizontal such that the patient's head is below his orher feet in relation to the horizontal. This position is useful duringcardiac surgery and scanning in the heart region. Acounter-Trendelenburg position is one where the patient's head is abovetheir feet. Linear movement device 42 is arranged to move the patientsupport relative to pivot and lock arrangement 40 and frame 32. When thepatient support 38 is in the vertical position (FIG. 4), the linearmovement device 42 can move the patient support 38 upwardly anddownwardly. Also, when the patient support 38 is in a vertical position,the support can be rotated about a vertical axis. When the patientsupport is in the oblique position, linear movement device 42 can movethe patient support in the oblique plane. For example, linear movementdevice 42 may include a fluid-operable piston and cylinder arrangement.In place of wheels 34, frame 32 can be equipped with slidable skids orair cushion supports for raising the frame slightly off the floor topermit movement. The frame 32 of the mobile patient-positioning device30 also may be supported for movement towards and away from the magneton an overhead monorail or other elevated rail arrangement. Finally,device 30 may be automatically moved into and out of the patientreceiving space by means of an automatic control device (not shown).

The patient support 38 is further equipped with a retractable orswingable foot stand 44; a retractable seat 46 and retractable handgrips or arm rests 48. A patient may be positioned on patient support 38and brought to essentially any desired orientation relative to frame 32and relative to the floor 22 or a horizontal position. For example, apatient may be positioned on support 38 in a standing position, withsupport 38 in a vertical or near vertical orientation and with thepatient standing on foot rest 44. Preferably, the patient leans onsupport 38 while standing. The patient also may be positioned on seat46. Alternatively, the patient may lie on the surface of patient support38.

The components of the mobile patient-positioning device 30 are formedfrom non-metalic materials such as, for example and, preferably,polymers or other dielectric materials. Device 30 does not substantiallyinteract with the magnetic fields produced by magnet 10 and thus doesnot impair the magnetic resonance imaging process.

A patient may be positioned on one mobile patient-positioning device 30and brought to the desired position and orientation while that device 30is remote from the magnet 9 and while the magnet 9 is being used toimage another patient, preferably held on another, similar mobilepatient-positioning device. Thus, the time consumed in positioning andorienting the patient does not detract from the productivity of thescanner, including magnet 9. The magnet 9 is only occupied by a givenpatient during the time required to conduct the actual scan of thepatient and during very brief intervals required to wheel the mobilepatient-positioning device 30, with the patient prepositioned thereon,into the patient receiving space 16. To assure accurate positioning ofthe mobile patient-positioning device relative to the magnet 9 and henceassure accurate positioning of the patient, the floor 22 or the magnetframe 10 itself may be equipped with rails or guides or tracks whichmate with corresponding features on the mobile patient-positioningdevice 30. For example, wheels 34 may be grooved or flanged, and may runon rails or grooves in floor 22. A first set of rails, guides or tracksmay run substantially in the direction of the patient entry 20. A secondset of rails and the like may run substantially perpendicular to thefirst set. A second patient may be disposed on a patient-positioningdevice which is itself positioned to run on the second set of rails. Inthis manner, the second patient is positioned in a ready state, waitingto be moved into position for MRI scanning. Preferably, the first andsecond set of rails are positioned adjacent each other on the floor sothat they intersect and allow for movement from one set to the other.

The ability to position each patient in essentially any orientationallows scanning while the patient is in essentially any posture. Thisimproves the realism of the scanned image and allows detection ofposture-dependent problems. For example, a patient having difficultieswith a knee joint can be imaged while the joint is bearing weight, withthe patient in an essentially standing position. Also, internal organscan be brought to the positions which they occupy while the patient isstanding or seated. For example, it is advantageous to performintestinal surgery on a patient when that person is in a verticalposition. The ability to move the patient-positioning device upwardlyand downwardly allows scanning of essentially any part of the patient.Typically, the pole axis 14 (FIG. 2) is about 5-6 feet (about 1.5-2.0meters) above floor 22 so that the head of a standing adult patient canbe positioned at or near the pole axis. The ability of the mobilepatient-positioning device 30 to elevate the patient, by action oflinear movement device 42 allows other parts of the patient to bebrought into alignment with the plural axis and hence to be imaged. Themagnetic flux return frame or yoke 10 and the coils may be hidden fromthe patient by a false or cosmetic wall surrounding the same.

As illustrated in FIGS. 9, 10 and 11, a similar C-shaped magnet 61 mayinclude a built-in patient elevator 62. The C-shaped magnet 61 may bepositioned above a false floor 64 so that the patient may walk onto theelevator platform 66 while the platform 66 is aligned with the falsefloor 64 and the elevator platform 66 may then be raised or lowered toposition the patient at the appropriate height relative to the magnet 61and relative to the plural axis 14.

The two approaches described heretofore may be combined. Thus, a mobilepatient-positioning device 30 as illustrated in FIGS. 1-8 may be usedwith a fixed patient elevator 60, so that the patient is positioned atthe appropriate orientation on the mobile patient-positioning device.The device 30 is rolled onto the elevator platform 66. The elevatorplatform 66 is then raised and lowered as necessary.

In a further alternative, a fixed elevator need not incorporate aplatform, but instead may be arranged to engage the frame 32 of themobile patient-positioning device 30, as by a fork or rods on theelevator 62 engaging in holes on the frame of the mobilepatient-positioning device 30.

A preferred method of MR Scanning of a patient with the long axis of thebody in a vertical orientation would proceed as follows:

With the patient support 38 in a vertical position as shown in FIG. 4,the patient steps onto the retractable foot stand 44. During this stageof the method, the patient support 38 is maintained at a convenientheight for the patient to step onto the foot stand 44 from the floor 22.Although foot stand 44 is depicted as slightly above the level of thefloor in FIG. 4, the patient support 38 optionally may be lowered toposition the foot stand level with the floor, thereby furtherfacilitating access by infirm patients.

The patient is then positioned and made comfortable. This step mayinclude the patient grasping the retractable hand grasps or arm rests48. The patient also may lean on support 38 while standing. In addition,additional cushioning, such as pillows and inflatable supports, may beprovided to increase the patient's comfort. The patient-positioningdevice 30 is then moved into the patient receiving space 16 where theadditional positioning of the patient up or down is achieved by means ofthe linear movement device 38. This aspect of patient-positioning willlocate the anatomical region of interest for MR scanning at the properposition in the patient receiving space 16. At this point, the MRscanning data acquisition will proceed.

Following completion of MRI data acquisition, the patient-positioningdevice 30 is removed from the patient receiving space 16. In thisrelocation step, the patient support 30 may be lowered or raised to aconvenient height for the patient to step off of the foot stand 44 ontothe floor 22. This may be accomplished before or after removing thepatient-positioning device 30 from the patient receiving space 16. Thepatient may then dismount the patient-positioning device 30.

There are variations of this preferred embodiment which should beevident in light of the foregoing description. First, the patient, whenstanding on the retractable foot stand, may be oriented in any directionas may be defined by rotation along the long axis of the patient's body.To this end, the pivot and lock arrangement 40 may be provided withadditional pivots, gimbals or other mechanisms which allow patientsupport 38 to pivot relative to frame 32 about its long axis L oranother axis parallel thereto, and/or to pivot about a vertical axis Vrelative to the frame (FIG. 6). Alternatively or additionally, thewheels 34 or other mobile support device supporting the frame 32 mayinclude pivotable casters or other devices which allow the frame to beturned around a vertical axis relative to the floor 22. Also, slightdeviations or tilts of the patient's body, and of the long axis L fromthe true vertical orientation may be used. Finally, if the objective ofthe MRI procedure is to scan an anatomical region of interest in theupper portion of the patient's body in a vertical orientation, thepatient may be seated on retractable seat 46. In the preferredembodiment, after stepping onto the patient-positioning platform, thepatient would sit on the retractable seat 46 prior to proceeding withthe MRI scan.

In yet another variant, the patient-positioning device 30 may remainfixed within the patient-receiving space 16, and the patient can walkinto the patient-receiving space and stand on or against the patientsupport 38. For example, the patient may step onto the foot stand 44.Alternatively, the patient can sit on seat 46. If the equipment is to beused only in this manner, frame 32 can be fixed relative to the MRImagnet and/or integral therewith. The configuration of the magnet allowsconvenient walk-in patient entry.

MRI is a useful modality for monitoring the progress of surgicalprocedures. A further aspect of the present invention extends thisutility in surgical applications, as can be seen in FIG. 1. A surgeonand associated medical personnel as necessary to perform a surgicalprocedure, can occupy a medical personnel area 50, between the legs ofthe C-shaped frame and/or in the area 52 immediately outside ofpatient-receiving space 16. With the patient support 38 in a horizontalposition, the patient is positioned in the magnet gap area, followed bythe desired height adjustment as described above. The surgeon is thenable to perform a surgical procedure, with the guidance of MR imaging.Such an embodiment is particularly advantageous for surgery performed oneither end of the body including areas such as the head, neck or thefoot ankle and knee in the case where the patient is positioned in themagnet feet-first. As an alternative embodiment, the medical personnelarea may be located outside the magnet and proximate the magnet gaparea, providing comparable access to the patient for surgery.

The ability to position a patient in a vertical orientation, as bypositioning patient support 38 in vertical orientation with the patienteither standing or sitting and perform MR imaging during a surgicalprocedure, enables novel surgical methods to be employed. For example,it would be advantageous to have the ability to perform intestinal orother abdominal surgery on a vertically oriented patient. Additionalsupports may be used to stabilize the patient when in a verticallyorientated position. These supports preferably are pillows or inflatablecushions. Also, with the patient in a sitting position, a surgeon mayperform knee surgery on the knee in a flexed position if desired. Inthese embodiments, the surgeon and associated medical personnel mayoperate from either medical personnel area as described above.

Apparatus in accordance with another embodiment of the presentinvention, as shown in FIGS. 12-14, includes a magnetic resonanceimaging magnet 109 which may include a ferromagnetic flux return or yoke100. In this embodiment, the yoke 100 is submerged under a false floor164. The magnet 109 is substantially the same as the magnet 9 shown inFIGS. 1-8, wherein the yoke 100 defines a pair of opposing poles 112projecting towards one another along a horizontally-oriented pole axis114 (FIG. 13). A patient receiving space 116 is defined between thepoles 112. Flux generating means 118 encircling portions of the frame100 are provided.

In this particular embodiment, since the flux return yoke 100 is belowthe floor 164, there are two possible open directions of patient entryas indicated by arrows 200. This dual entry configuration facilitatessequential scanning of patients either in a one way direction or a twoway direction. In the one way direction setup, a patient may be movedinto the patient receiving space 16 while at least a second patient isprepared just outside the magnet 109 on the same side where the firstpatient entered the magnet. After the first patient is scanned, he orshe is moved forward and out of the patient receiving space 16 to theopposite side of the magnet. Next, the second patient is moved inallowing for a continuous stream of patients with minimum downtime forthe MRI scanner. In the alternative two way setup, one patient may bemoved into the patient positioning space 16 from left to right, forexample (FIG. 14). The second patient may be positioned outside of themagnet 109 to the right. When the first patient's scan is complete, heor she may be moved out to the left while the second patient is movedfrom the right to left into the patient receiving space 16. Thisconfiguration also facilitates MRI-assisted surgery and other proceduresrequiring medical personnel to be within the magnet's poles 120. Asthese and other variations and combinations of the features discussedabove can be utilized, the foregoing description of the preferredembodiments should be taken by way of illustration rather than bylimitation of the invention set forth in the claims.

What is claimed is:
 1. A mobile patient-positioning device comprising:(a) a frame; (b) a patient support mounted to said frame for movementthrough a range of orientations relative to said frame, said patientsupport including a footrest; and (c) a transporter operable to movesaid frame relative to a magnetic resonance imaging magnet so that apatient on said patient support can be positioned in a patient-receivingspace of such magnet with said patient support in any of a plurality ofdifferent orientations within said range of orientations, said pluralityof different orientations including an upright orientation in which apatient carried by the patient support is standing on said footrest. 2.A device as claimed in claim 1 wherein said transporter includes wheelssupporting said frame.
 3. A device as claimed in claim 1 furthercomprising an elevator operable to lift said patient support upwardlyand downwardly relative to said frame.
 4. A device as claimed in claim 1in combination with an elevator mounted in a fixed location relative tosaid magnet, said elevator being adapted to move said frame upwardly anddownwardly relative to said magnet when said frame is disposed adjacentsaid magnet.
 5. A device as claimed in claim 1, wherein said foot restis retractable.
 6. A device as claimed as claim 1, wherein said patientsupport further comprises grab handles so that a patient can assist inimmobilization during a MRI scan.
 7. A device as claimed in claim 6,wherein said grab handles are retractable.
 8. A mobilepatient-positioning device comprising: (a) a frame; (b) a patientsupport mounted to said frame for movement through a range oforientations relative to said frame, said patient support including aseat; and (c) a transporter operable to move said frame relative to amagnetic resonance imaging magnet so that a patient on said patientsupport can be positioned in a patient-receiving space of such magnetwith said patient support in any of a plurality of differentorientations within said range of orientations, said plurality ofdifferent orientations including an upright orientation in which apatient carried by the patient support is sitting on said seat, wherebya patient can be positioned in a sitting position during a MRI scan. 9.A device as claimed in claim 8, wherein said seat is retractable.
 10. Adevice as claimed in claim 8 wherein said transporter includes wheelssupporting said frame.
 11. A device as claimed in claim 8 furthercomprising an elevator operable to lift said patient support upwardlyand downwardly relative to said frame.
 12. A device as claimed in claim8 in combination with an elevator mounted in a fixed location relativeto said magnet, said elevator being adapted to move said frame upwardlyand downwardly relative to said magnet when said frame is disposedadjacent said magnet.
 13. A mobile patient-positioning devicecomprising: (a) a frame; (b) a patient support mounted to said frame formovement through a range of orientations relative to said frame; and (c)a transporter operable to move said frame relative to a magneticresonance imaging magnet so that a patient on said patient support canbe positioned in a patient-receiving space of such magnet with saidpatient support in a plurality of different orientations within saidrange of orientations, wherein said patient support is mounted to saidframe by a pivot, said patient support being pivotable about said pivot,and translatable relative to said frame and said pivot.
 14. A device asclaimed in claim 13, wherein said patient support has a planar surfacefor supporting said patient, said planar surface being pivotable aboutsaid pivot along with said patient support, said planar surface alsotranslatable along with said patient support along the plane defined bysaid planar surface.
 15. A device as claimed in claim 13, wherein saidpivot has a substantially horizontal axis.
 16. A device as claimed inclaim 15 wherein said patient support can pivot relative to said framebetween a horizontal orientation and a vertical orientation.